Hydraulic hoisting unit and control system therefor



Jan. 11, 193s.

H. F, vlcKERs HYDRAULIC HOISTING UNIT AND CONTROL SYSTEM THEREFOR Original Filed Sept 22,

y FHIINJ Nil INVENTOR.

ATTORNEYl Jam. l1, 1938.

H. F. vlcKERs 2,104,780`

HYDRAULIC HOISTING UNIT AND CONTROL SYSTEM THEREFOR Original Filed Sept. 22, 1933 7 Sheets-Sheet 2 N l.; M2 I 'INVENTOKR ATTORNEYS Jan. 1l, 1938. H. F. vlcKl-:Rs 2,104,780

HYDRAULIC HOISTING UNIT AND CONTROL SYSTEM THEREF'OR original' Filed sept. 22. 1935 7 sheets-sheet 5 BY I 6M,m JW@ ATTORNEYS Jan. l1, 1938. H. F. vlcKERs 2,104,780

HYDRAULIC HOISTING UNIT AND CONTROL SYSTEM THEREFOR original F11-'ed sept. 22, 1953 7 sheets-sheet 4 ATTORNEYS Jan. 11,1938. H.' F. vlcKERs 2,104,780

HYnAULIc HosTINe UNIT AND oNTnoL SYSTEM THEREFOR' Original' Filed sept. 22, 4193.1, 7 sheets-sheet 5 Q Arro H. F. VICKERS Jan. 11, 1938.

HYDRAULIC 'HOISTING UNIT AND CONTROL SYSTEM THEREFOR 7 sneetslsneet e Original Filed Sept. 22, 1933 INVENTOR. -f/y F. Weke/ 5 5MM, MIK/ Y ATTORNEYS Jan.'11, 193s. H F wcKERs 2,164,780

HYDRAULIC HOISTING UNIT AND CONTROL SYSTEM THEREFOR originl Filed sept. 22, 1933 7 sheets-sheet 7 ATToRNYs 6 is relieved of operating pressure except during the actual hoisting operation. This results in a considerable power saving, as otherwise the single large volume pump would have to operate at full pressure at all times. Oil also iiows through 'the small pump unit 8 into the chamber I4, which chamber also surrounds a valve I5, The valve I5 is provided with a small piston I6, and the flow from the chamber I4 to the right hand side of the piston I6 is by means of a threaded resistance passage 15 formed between the parts I1 and I8, the chamber to the left of the piston I6 being vented through the conduit I9 to make the pressure in the chamber to the right of the piston, designated 20, eiective. A

As the pump 8 is continuously operated, the oil under pressure flows through the passageway and chamber I4 through the resistance passage and into the chamber 20, exerting thrust to the left which tends to overcome an adjustable tension spring 2|. By 'overcoming the spring 2| the pressure in the chamber causes the valve I5 to move slightly to the left and take up a position whereby oil is bypassed into the A chamber 22 which leads to the main operating passageway 9a, whereby oil is Ybyrnassed into the chamber 22 in just suilicient amount to maintain a balance;

between the pressure in the chamber 20 and the resistance of the spring 2|, the oil being restricted in its flow from the chamber I4 to the chamber 20 aproper amount to tend to maintain this balance; or, in other words, this restriction is sufficient to prevent chattering and sudden movement of the valve. 'I'his condition results in valve I5 functioning as a relief valve during the time that the pressure in the chamber 22, and, of course, the main outlet passage 9a, is below the adjusted pressure of the spring 2| with the result that a predetermined pressure is maintained in passageway and chamber I4 at all times so as to denitely assure operating pressure for the control parts of the system.

When this control pressure which flows from the chamber I4 through the line I0 to the unit 3a (see Fig. 1) is utilized to operate the control unit to hoist, the pressure in the outlet 9a and chamber 22 rises, causing a back pressure'against the overow of liquid flowing from the chamber I4, tending to further overcome the spring 2| and open the valve I5 from its normal correct position. In the function of this circuit we may assume an adjusted operating pressure of ve hundred pounds per square inch on the spring 2| and a nal operating pressure of seven hundred pounds or more in the outlet 9a and the chamber 22. When the main pump line 9 is so restricted as to exceed this ve hundred pounds pressure, such pressure is delivered into chamber 20, with the direct result that this considerably exceeds the adjusted tension of spring 2|, causing the piston I6 on the valve I5 to move to its extreme operating distance to the left, whereby allowing free flow of oil from the chamber I4 to the chamber 22. This results in the output of the small pump 8 being delivered to do useful work along with the output ofthe largel pump 6. l,

The result and operation of this circuit under the above assumed condition is that` pressure would be maintained in the chamber I4 at a minimum of ve hundred pounds per square inch, and pressure in the outlet 9a would vary from approximately zero to seven hundred or more pounds per square inch. It will thus be seen that this structure and circuit permit a large volume ot liquid being supplied to operate the motor at a relatively high operating pressure, and at predetermined intervals, and at the same time maintaining a somewhat lower operating pressure in the chamber I4 to assure a constant pressure supply in the line I0, which leads from the chainber I4, to the pilot or operating valve 3a and to the braking unit 5.

Referring particularly to the control. unit 3, as best'shown in Figs. 1 and 6, it will be seen that the large volume pump assisted by the small volume pump supplies pressure through the line S and into the chamber 23 of the main control valve unit 3. This chamber 23 surrounds an automatic volume control valve 24 and also extends to a position where it surrounds and com` municates with a directional control valve 25.

A conduit 26 connects the control valve 3a withA the left hand side of the directional control valve 25 so that, by movement of the control valve 3a, pressure is admitted from the line I0 into the conduit 26 to shift the directional valve 25 to the right. This action permits oil to ilow from the line 9, through chamber 23, into the chamber 21, which chamber is connected through to passage 28 which leads to the motor 4.

The valve 24 -is provided with a piston valve having a piston portion 29 which is provided with ends or piston rods oneach side of equal diameter. The piston 29 is normally urged to the right by a spring 30 of predetermined tension to normally prevent the flow of oil under pressure from the chamber 23 into Athe outlet passage 3| which leads to the return tank R. It will be seen that the valve 24 will remain on its seat as long as the pressure in the chamber 23, communicated through passageway 32 to a chamber 33 at the left hand side of the piston 29, plus the predetermined thrust of the spring 30, is ,suilicient to force all the pump output through the orifice, which is formed by the wall of the chamber 21 and the tapered portion 34 of the valve 25 when the'valve 25 is 'moved to the right, as viewed in Figs. 1 and 6. It should be noted here that, as shown in dotted lines in lig. 1 l l 1, the passageway 32 is'directly connected with the chamber 21; the extreme right hand of the passageway 32 being in communication with the exhaust chamber 60 when the valve 2,5 is moved to the left, as will be later explained. By way of example, it will be seen that if the spring 30 back of the piston 29 has a thrust equivalent to twenty pounds per square inch, such piston will maintain a closed position relative to the passage 3|, until such time as the vvolume of liquid passing through the chamber 23 requires more than twenty pounds per square inch to force this volume of'liquid through the clearance between the wall of the chamber 21 and the tapered portion 34 of the valve. It will thus be seen that the valve 24 will provide a definite pressure drop across an orice of given size, resulting in a denite rate of flow through this oriiice. It will thus be seen that the amount oi' taper 34 on the valve 25 becomes a method of fixing the speed rate of hoisting. y f

The valve 25 is provided with a cam-35 which normally contacts with a cam follower 36 when such valve 25 is in neutral position. Movement of the valve to the right, as above described, also moves the cam 35 to the right which in turn permits the follower 36,-to be raised because of spring pressure behind a valve or plunger 31l formed in an auxiliary portion 3b of the control unit 3. Raising of this valve 31 permits pressure to iiow from the line |0a into-1ine38, which 75l line 35 connects intoa chamber 39 forming a part of the automatic brake structure. As best shown in Figs. 4 and 5, this brake structure consists of supportedfpivoted arms 43 and 5i. These arms and the brake shoe portions 42 carried thereby are normally forced against the brake drum @i3 because of springs M so that normally 4the arms t@ and i grasp and hold the brake drum mechanically. The cylinder 39 is positioned intermediate the arms `5B and 4i and carries oppositely acting pistons 45, with the result that sub stantially simultaneously with the raising of the valve 31, the pressure from the line ma will be communicated through the`line 33, intothe cylinder Surging the pistons 45 outwardly to contact with and release the brake shoes 22.

It is desirable during non-hoisting operation' to allow the pump oil to ow from the chamber 23 through the exhaust passage 3i back to the return tank or reservoir R. This is accomplished by' normally venting the passage 33, which is at the rear of the piston 29 to the atmosphere, so that any pressure in the chamber 23 exceeding the resistance of the spring 33 will cause the valve 2d to move to the left. A valve 31a being normally downwardly spring pressed, will, when the plunger 3i is forced downwardly, due to the directional valve 25 returning to neutral position, connect the chamber 33 with the atmosphere or, more specically speaking, the return line, by means of the conduit 45, conduit 36a connecting the cylinders of 31a and 31, and conduit 55h connecting the cylinder of 31 with the relief or drain conduit 48. y

During the hoisting operation, the brake shoes `being released by the application of pressure to 31a. upwardly and thus closing the exhaust vent so that during this period the chamber 33 is open to the effective pressure from; the line 32. It will be seen that this construction and circuit are effective to positively relieve the large pump 8 from operating pressure except when hoisting. The hoisting unit 5, as shown in Fig. 1, andbetter illustrated in Figs. 7 to l0, embodies a balanced gear motor of the general construction described in my copending application Serial No. 557,862, filed August 18, 1931, teeth subjected to pressure in the pressure chamber at one side of the motor being balanced by pressure chambers 28a and the teeth on the other side, namely those on the exhaust side being relieved by balancing chambers sia,

When the valve 2e is closed and the valve 25 moved to the right to permit the iiow of liquid under pressure into the conduit 25, the hoisting motor, generally designated is actuated to rotatejhe shaft ,5i and the drum 59. As best shown in Figs. 1', 3 and l0, the other end of this shaft 5i carries a brake member i3 and also a traveling nut 52, connected with arms 5B pivoted as at 53 to transmit motion to a sliding sleeve 55. This sleeve 55 surrounds anuextension of the valve 25. A threaded portion 52a which operates the traveling nut 52 is provided with threads of such pitch, proportioned in accordance with the leverage of the arms 55 and the` hoisting distance or height so that when the member being hoisted approaches the extreme limit of such hoisting distance, the sliding sleeve 55 contacts with adjustable nuts 56. so that during the last portion of the movement', the sliding sleeve 55 will m'ove the valve 25 towards central or neutral position to gradually stop the flow of liquid to the chamber 21 from the chamber 23. This same movement depresses the plunger 3l and permits the valve @la to lower to exhaust the chamber 33 to permit movement of 5 the piston 29 to the left. Thus stopping movement of the motor 4 and also simultaneously cutting oi the pressure from the line lila and evacuating the chamber 39, allow the brake springs to apply brake pressure and hold the hoist at the place where it has just stopped, due to movement of the directional control valve 25. The tendency to hoist by the motor is not completely removed until after the brakes are applied; this is accomplished by using a spring backed valve 31a of less strength than the back pressure built up by the sudden exhausting of oil from the cylinder 35 by the springs M.

Movement of the control valve 3a in the opposite direction eiects lowering of the elevator or 20 hoist unit in that pressure from the small pump 3 is conducted through the line 5l to the chamber at the right of the valve 25 (see Fig. 1) to shift the 'valve to the left. This movement relieves the lpressure in line 26 and also results 25 in applying of pressure to the line 38 to operate the pistons 25 and to relieve the brake shoes as previously described.

During this lowering action, the motor il will i operate as a pump and, referring tc Figs. 1 and 30 6, it will be seen that oil in the passage 28 will :dow through a chamber 58 to a passageway 59 and due to the position of the Valve 25, when mbved to the left, will pass into passageway 55 connected to the reservoir. The connection be- 35 tween the chambers 58 and 55 is controlled by a valve 5i formed integrally with a piston 52. This valve 6i is normally urged to the right, as viewed in Fig. 6, by a spring 63 of predetermined ten-I sion. As best shown in Fig. l, chambers 6|! and 55 Aare connected to passageway 59 by means of conduit 55a, thus permitting any pressure in passageway 59 to tend to overcome the tension of the spring 53,"and in turn causing the valve 5i to restrict the passage of oil from the chamber 4:5 58 to the passageway 59.

An unrestricted passageway 66 directly connects the chambers til and 65a (as shown in dotted lines in Fig. l) thus permitting the pressure in passageway or chamber 50 to aid the 50 spring 53 in resisting the eiect of pressure in the passageway 59. In operation, during the lowering of the hoist, the piston 52 and valve 5i will take up a position wherein the diiierence in pressure existing in chamber 59 and chamber 55 55 will be equivalent to the resistance of the spring 53 against i'luid pressure in chambers 5 and 55.

A tapered surface 35a at the opposite end of the valve from the tapered surface 35 will, when 3 the Valve 25 `moves to the left, act as an orice between the chambers 59 and 6D., Therefore, it will be seen that the balancing ofthe piston 52 and valve 5i determines a pressure drop across the orifice formed by the degree of taper between 65 the surface 35a and the wall of chamber 59 resulting in a. fixed iiow rate which in turn results in a iixed descending rate for the elevator or hoist, all accomplished by controlling the exhaust from the motor 5 land through the cham- 70 ber 28.

It will thus be seen that different rates of hoisting and/or lowering cabe obtained by the simple step of placing a new v c member 25 in the control unit having a taper 34 and 34u75 predetermined in accordance with the particular hoist for which it is to be used; it being understood, of course, that the degree of taper on 34 and 34a. may be different, dependent upon the relative rate of hoisting, lowering, and deceleration desired in the particular job.

Descent of the hoist or elevator continues until the traveling nut 52, moving in the opposite direction, actuates the sleeve 55 until contact is made with the adjusting nuts 61 and thus movingvalve 25 toward neutral position, and gradually decelerating. and then stopping the descent of the hoist or elevator. Cam 35 again lowers the plunger 31 to exhaust cylinder 39 allowing the brakes to be applied to hold the hoist in its stopped position.

The conduit 32, see Fig. 1, has a double function in that it not only acts in assisting to maintain a constant head across the orice formed by the surface 34 during hoisting, but also functions in combination with the valve 68 to provide a maximum pressure control of the pump supply during hoisting, thereby providing maximum acceleration and control during the hoisting stroke. Referring more particularly to Fig. 6,

the valve 68 includes a spring 69, the strength of which may be relatively adjusted by the mechanism 10 so that the'spring 69 holds the valve member 1I on its seat until the pressure in the chamber 33 exceeds the resistance of the valve 1l and spring 69. If the pressure in chamber 33 should develop sufliciently to unseat the valve 1|, liquid will pass by saidv valve and through the drilled hole in the valve member 24, with the result that the valve 24 and piston 29 will rapidly unseat to bypass the surplus oil to the tank, the valve 24 and piston 29 in this conlnection acting as a relief valve similar to the relief valve disclosed in my application Serial No. 552,692, led July 23, 1931, inasmuch as the passageway 32 is smaller than the passageway 12 leading from the chamber 33 to the valve 1|. It is therefore obvious that the valve 24 acts as a non-chattering relief valve a-nd that any increase in pressure in the chamber 23 beyond thev maximum pressure seating of the valve 1 I, which controls the pressure in the Achamber 33, will cause the valve 24 to unseat, allowing excess oil to pass from the chamber 23 to chamber 3| and to thev return tank. 'I'hus this valve acts both as a means for maintaining constant head across the xed orifice and also as a relief valve for controlling maximum pressure.

When the valve 25 moves to the left, the tapered portion 34a will uncover the extreme righty hand end of passageway 32 and open same to the exhaust conduit 60, unseating the valve 24.

Attention is called to the important point that the combined relief and unloading valve permits the small volume pump to operate at the same pressure as the large volume pump, otherwise it would operate at a. higher pressure during hoisting.

It will be seen that the degree of taper 34 and 34m on the valve 25 will provide deceleration at any rate desired, and in all cases will effect a' smooth stop. The unloading valve 31a in cornbination with valve 31 effects release of the main pump only after pressure from brake mechanism has been released, to prevent power release before the mechanical brake is set.

What I claim is:

l. A hydraulic hoist system comprising a source of'pressure supply, a motor-pump unit for said hoist, directional control means, orices lowering.

2. A hydraulic hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means, orifices through which liquid flows to and from said unit, means responsive to the position of said control means for effecting a predetermined pressure drop across said orices whereby to control the rate of movement during hoisting or lowering, normally applied mechanical brakes for said hoist, and means responsive to movement of said directional control means for hydraulically releasing said brakes.

3. A hydraulic hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means, orifices through which liquid flows to and from said unit, means responsive to the position of said control means for effecting a predetermined pressure drop across said orifices whereby to control the rate of movement during hoisting or lowering, normally applied mechanical brakes for said hoist, means responsive to movement of said directional control means for hydraulically releasing said brakes, and means responsive to the movement of said control means to neutral ow stopping position for allowing positive application ci the mechanical brakes.

4. A hydraulic hoist system comprising a source of pressure supply, a motorfpump unit for said hoist` directional control means, orifices through which liquid iiows to and from said unit, and means responsive to the position of said control means for eiecting a predetermined pressure drop across said orices whereby to control the rate of movement during hoisting or lowering, said source of supply including a main supply pump and a control supply pump and a combined relief and control valve normally maintaining control pressure throughout the system and admitting liquid from the control pump into the main pump when pressure in the main pump line exceeds the control pressure maintained by said valve.

5. A hydraulic hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means, portions-of said means forming orifices through which liquid ows to and from said unit, and means responsive to.

the position ofsaid control means for effecting a predetermined pressure drop across said orices whereby to control the rate of movement during hoisting or lowering.

6. A hydraulic hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means, orifices through which liquid flows to and from said unit, and

means responsive to the position of said control means for effecting a predetermined pressure drop across said orifices whereby to, control the rate of movement during hoisting or lowering, one of said last named means also serving to control the maximum pressure supply.

7. A hydraulic hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means, portions of said means forming oriiices through which liquid flows to and from said unit, and means responsive to the position of said control means for effecting a predetermined pressure drop acrosssaid orices whereby to control the rate of movement during 15 hoisting or lowering, one of said last named means also serving as an automatic volume control.

A hydraulic'hoist system comprising a source of pressure supply, a motor-pump unit for said hoist, directional control means. orifices through which liquid ilows to and from said unit, means responsive to the position lof said control means for effecting a 'predetermined pressure drop across said orifices whereby to control the rate of movement during hoisting or lowering, normally applied mechanical brakes for said hoist, means responsive to movement of said directional control means for hydraulically releasing said brakes, said source of supply'including a main supply pump anda control supply pump, and a combined relief and control valve normally maintaining control pressure throughout the control system and maintaining said control pressure while admitting '4 liquid from the control pump into the main pump when pressure in the main pump line exceeds the control pressure maintained by said valve.

9. A hydraulic hoist system, comprising a source of pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional control means towards neutral position to stop the ow of liquid and stop the hoist, and means responsive to said movement of said directional control means for eiecting application of said brakes to hold the hoist in its arrested position and a ilow control cooperating with said control means when moved in one direction to receive fluid pressure from said unit operating as a pump t control the rate of lowering of the hoist.

10. A hydraulic hoist system, comprising a source oi pressure supply, a motor-pump unit for said hoist, combined'mechanical and hydraulic brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional control means towards neutral position to stop the flow of liquid and stop the-hoist, means responsive to said movement of said directional control means forreleasing said hydraulic and applying said mechanical brake structure to hold the hoist in its arrested position, and means for retarding said release and application.

'11. A hydraulic hoist system, comprising a source of pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional control means towards neutral position to stop the ow of liquid and stop the hoist, means responsive to said movement of said directional control means for eecting application of said brakes to hold. the hoist in its arrested position, means for moving said directional control valve in either direction from said neutral position to effect raising or lowering of the hoist, said directional control valve cooperating with pressure chambers to 75 asmoothvstop, means responsive to said moveform ilxed orifices in each of said positions, and means for maintaining a predetermined difierential across said oriiices in either of said positions.

l2. A hydraulic hoist system, comprising a source of pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional control means towards neutral position to control the iiow of liquid and reduce the speed of the hoist at a predetermined rate to accomplish ment of said directional control means for effecting application `of said brakes to hold the hoist in its` arrested position, means for moving said directional control valve in either direction from said neutral position to effect raising or valve cooperating with pressure chambers to form xed oriiices in each of said positions, and means for maintaining a predetermined diilerential across said orifices in either of said positions, one of said means for predetermining the dinerential across one of said orii'ices including means for controlling the maximum pressure in said source of pressure supply.

13. A hydraulic hoist system, comprising a sourceiof pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, meansl actuated by the position of the hoist for moving said directional control means towardsneutral position to stop the ow of liquid and stop the hoist, and means responsive to said movement of said direction control means for effecting application of said brakes to hold the hoist in its arrested position, said pressure supply including a large volume actuating pump and a small volume control pump.

14. A hydraulic hoist system, comprising a source of pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional control means towards neutral position to stop the flow of liquid and stop the hoist, means responsive to said movement of said directional control means for effecting application oi said brakes to hold the hoist in its arrested position, means for moving said directional control valve in -either direction from said neutral position to eiect Araising or lowering of the hoist, said directional control valve cooperating with pressure chambers to form fixed orices in each of said positions, and means for maintaining a predetermined-diierential across said orifices in either of said positions, said pressure supply including a large volume actuating pump and a small volume control pump.

, 15. A hydraulic holst system, comprising a source vof pressure supply, a motor-pump unit for said hoist, brake structure for said hoist, directional control means, means actuated by the position of the hoist for moving said directional lowering of the hoist, said directional control control means towards neutral position to stop the A ilow of liquid and stop the hoist, means responsive to said movement of said directional control means for eiecting application of said brakes to hold the hoist in its arrested position, means for moving said directional control valve in' either Vdirection from said neutral position to effect raising or lowering of the hoist, said directional control valve cooperating with pressure chambers to form xed orices in each oi said positions, and means for maintaining a predetermined difierential across said orice in either of said positions to control the speedpof raising and lowering, one of said means for predetermining the dierential across one of said orices including means for controlling the maxlrnnm pressure in said source of pressure supply, said pressure supply including a large volume actuating pump and a small volume control pump.

16. A hydraulic hoist system, comprising a n source of pressure supply, a 'motor-pump unit.

tional control means towards neutral position to control the ilow oi' liquid and reduce the speed of the hoist at a predetermined rate to accomplish a smooth stop, means responsive to4 saidy movement of said directional control means for eilectlng application oi said brakes to hold the hoist in its arrested position, means for moving said directional control means in either direcf tion from said neutral position, and a iiow control cooperating with said control'means when *moved predetermined rate to accomplish a smooth stopt means responsive to said movement oi said direc tional control means for effecting application of vsaid mechanical means to hold the hoist in its arrested position, and means for hydraulically moving said directional control means in either direction from said neutral position to effect raising or lowering of the hoist.

18. A hydraulic hoist system, comprising a source of pressure supply, a hydraulic power unit directly connected to the hoist for operating same, mechanical means for locking the power unit in hoisted position, and means hydraulically connected to said source of pressure supply and said power unit and actuated by the movement of .the movablel element of said power unit towards hoisted position and operating in combination with said mechanical locking means to insure a positive locking of the power unit and the holstbefore the release of hoisting pressure from said source of supply and in said system.

HARRY F. VICKERS. 

